Teun Remmers

124 | Chapter 8 Abstract Introduction : The afterschool time segment is considered a promising period for Physical Activity (PA) promotion in children. In this time segment, characteristics of the built environment may play an important role. Therefore, the objective of this study was to assess relationships between features of children's environment and context-specific afterschool leisure time PA and active transport, with the emphasis on relationships with greenspace environment, roads, and publically accessible playgrounds. Methods : Children participated in a 7-day accelerometer- and Global Positioning Systems (GPS) protocol. GPS data-points were overlaid with GIS data using ArcGIS 10.1 software. Afterschool periods were identified based on school schedules and validated individually based on children's GPS locations at their school parcel. Afterschool leisure time PA was identified by filtering from combined accelerometer-GPS data at participant's residence, school, sports grounds, afterschool childcare centres, shopping centres, and in trips. Trips were identified according to previously validated GPS speed-algorithms in the PALMS database. For each child, a multi-place environment was calculated combining home-, school-, and the daily transport (between home and school) environment. GIS-derived features of the built environment were extracted from these mutli-place environments. Multi-level linear mixed models were fitted, adjusted for meteorological circumstances. Outcome measures were afterschool leisure time PA, cycling and walking. Results : In total, 253 10-12-year-old children from 20 Dutch primary schools provided valid data. Thirteen percent of the afterschool leisure time was spent in moderate-to- vigorous PA (MVPA), while 37% of the afterschool active transport time was spent in MVPA. Afterschool leisure time MVPA was associated with smaller distances from school to home and a higher density of buildings, lawns, shrubs and pedestrian paths. In the same time, higher density of buildings, lawns, and pedestrian paths were associated with fewer minutes of afterschool cycling, while larger multi-place environments and a higher density of pedestrian area's and sports terrains was associated with more minutes of afterschool cycling. Afterschool walking was associated with smaller distances from school to home and a higher density of agriculture, shrubs, main roads, and pedestrian paths. Conclusion : We demonstrated that with accelerometer and GPS methodologies combined with extensive analyses of GIS data, studies can investigate associations between the specific features of the multi-place built environment and context-specific afterschool PA. The present study showed that greenspaces (i.e. lawns and shrubs) and smaller distances from children's residence to their school were associated with more afterschool leisure time PA and walking among 10-12-year old children. For afterschool cycling different features of children's environment are relevant.